Mobile telephones have long been employed to facilitate communication among users disposed in geographically dispersed locations. In recent years, the “on-the-go” lifestyle has turned mobile telephones from luxury goods to basic necessity items. One reason mobile telephones have become so popular is due to the small form factor. Unlike the earlier models, today's mobile telephones tend to be small, sleek, and ergonomic.
To facilitate discussion, FIG. 1A shows a simple diagram of a cross-sectional view of a mobile telephone 100. Although mobile telephones may have different designs, most mobile telephones have a bar configuration in which components are positioned next to one another mostly in the y-direction. In an example, mobile telephone 100 may have a plurality of components encased within a device housing 102. The plurality of components may include a set of keys 104, a display area 106, an audio transducer 108 (e.g., earpiece), and the like.
Set of keys 104 is usually positioned toward the bottom of mobile telephone 100. Usually, at minimum, set of keys 104 includes the number keys. However, some mobile telephones (e.g., smart devices) offer additional functions (e.g., email function, Internet, music function, etc.) besides voice calls. For these smart devices, a QWERTY keyboard may be provided to enable users to take advantage of these functionalities. Since set of keys 104 is an essential component of mobile telephone 100, set of keys 104 has to be large enough to ensure user's readability and usability. Thus, the form factor of mobile telephone 100 is at least limited by the size of set of keys 104.
Another component that may also affect the form factor of mobile telephone 100 is display area 106, which is usually positioned close to set of keys 104. Display area 106 is usually employed to display instructions, messages, menu items, and the like. Thus, display area 106 has to be large enough so that the user is able to view (e.g., read) the items presented in display area 106.
Positioned toward the top of mobile telephone is an earpiece that enables the user of mobile telephone 100 to hear sound emitted from the device. Those skilled in the art are aware that the sound emitted from the earpiece is usually produced from audio transducer 108, which is typically arranged parallel to an ear-facing surface 112. To produce the sound, audio transducer 108 may include a magnet structure coupled to a coil and diaphragm. When power flows through the magnet structure, the power interacts with the magnetic field produced by the magnet structure to cause the coil to move up and down. In turn, the diaphragm moves, thereby compressing the air in front of the diaphragm to create sound wave. The sound waves travel outward from audio transducer 108 through acoustic channel 110 to reach ear-facing surface 112, which is usually the location at which a user of mobile telephone 100 may place his ear to hear the sound emitted from mobile telephone 100. Since the quality of the sound usually degrades as the size of audio transducer become smaller, the size of audio transducer 108 has a finite size.
As can be seen from FIG. 1A, mobile telephone 100 may require certain components to be functional. Since most mobile telephones have the components positioned next to one another, the size of the components may affect the length of the mobile telephones. Given that the physical size of the mobile telephone is an important consideration in a consumer's purchase of a mobile telephone, most manufacturers try to identify ways to reduce the form factor of the mobile telephone. One method is to reduce the size of the components. However, since most components need to be of a finite size in order to be functional, the size of the mobile telephone has already been limited to the smallest possible size a component can be reduced to without sacrificing function.
One method for diminishing the length of a mobile telephone is to stack the components (as shown in FIG. 1B). Similar to FIG. 1A, mobile telephone 120 may include a plurality of components (a set of keys 124, a display area 126, an audio transducer 128, and the like) encased within a device housing 122. To reduce the length of mobile telephone 120, audio transducer 128 may be partially positioned behind display area 126. Accordingly, the stacked components reduce the length of mobile telephone 120; however, mobile telephone 120 sacrifices its sleek, thin design (i.e., thicker in the z-direction).
Additionally, the longer acoustic channel (130) may cause acoustic performance issue since sound waves tend to degrade as it travels further away from its source. Given the same condition, the quality and/or volume of the sound waves of FIG. 1B is significantly lower than that of FIG. 1A since the sound waves have to travel a further distance in FIG. 1B to reach an ear-facing surface 132. In addition, resonance tends to increase in a longer acoustic channel. Those skilled in the art are aware that sound waves bounce against other surfaces as it travel away from the audio transducer. Thus, as sound waves bounce against the wall of acoustic channel 130, the longer distance travel by the sound waves cause an increase in resonance, which may translate into a less-than-acceptable sound being emitted at ear-facing surface 132.
Another problem with the design of FIG. 1B is that the sound emitted from mobile device 120 may not meet the standard established for a hearing aid compatible (HAC) device. Given that a substantial percentage of the world population requires the assistant of hearing aid devices, mobile telephones that do not meet HAC standard may result in market share loss to the manufacturers. Since a longer acoustic channel may result in distortion to the sound waves being received by the user at ear-facing surface 132, the distorted sound may be further degraded as the sound waves travel through the hearing aid.
To address the potential problem that may exist in delivering sound waves to a user of hearing aid devices, some hearing aid devices allow the user to switch between sound wave mode and magnetic field mode. In the magnetic field mode, a telecoil (i.e., T-coil) within the hearing aid device is employed to pick-up the magnetic field being produced by audio transducer 128. In other words, the telecoil detects the magnetic field energy being emitted from audio transducer 128 and convert the detected magnetic energy into sound.
However, the magnetic field becomes weaker as the magnetic field lines travel away from its source. Thus, the magnetic field that may be picked up by the telecoil (as shown in FIG. 1B) is significantly weaker than the magnetic field of FIG. 1A since the acoustic channel is significantly longer. As a result, the sound that may be converted by the telecoil may be distorted or insufficiently loud/clear for proper comprehension. Thus, even though the length of mobile telephone 120 is shorter by placing audio transducer 128 behind display area 126, the longer acoustic channel causes distortion in the sound being emitted, thereby creating distorted sound which may result in a frustrating experience for the mobile telephone user, especially if the user requires the assistance of a hearing aid device.